金剛經纂要刊定記 6.63

6.63

言第一義者。以無著釋經皆約二諦。既五眼文中不言眼即非眼，又以見智二種其體不殊，故於最後安立第一義。第一義即是空寂，空寂即是不可得義，意皆同也。

Speaking of "the ultimate truth": because Asaṅga's explanation of the sūtra is consistently in terms of the two truths. Since the text on the five eyes did not say 'the eyes are not eyes,' and furthermore because the two—seeing and wisdom—are not different in substance, the ultimate truth is established at the very end. The ultimate truth is precisely emptiness and stillness; emptiness and stillness is precisely the meaning of unapprehendability; the meanings are all identical.